Arthroscopic surgery is a minimally invasive therapeutic and/or diagnostic procedure, during which small sized visualization and surgical tools are introduced into a joint body cavity (most commonly a knee) through very small incisions. Typically, at least three incisions are employed for a therapeutic procedure and at least two for a diagnostic procedure. During the surgery, irrigation of the joint is necessary for the following reasons:
(1) Distention of the joint is desirable for better visualization and access achieved by an increased joint or tissue separation. This is accomplished by application of pressure through the medium of the irrigation fluid to the tissue structure and causes closing of the blood vessels; PA1 (2) Flow of the irrigation fluid through the joint keeps the field of view clear and often evacuates most of the loose debris; PA1 (3) The fluid keeps the joint lubricated and replaces lost body fluids. PA1 (a) There are times during the surgical procedure when one needs to view and reach the far or posterior end of the joint. The joint separation needs to be increased without any need for an increased flow. A higher pressure in the joint will achieve this. PA1 (b) If there is debris or bleeding in the joint, a quick flush of fluid is needed to clear the field of view. Such conditions require a higher fluid flow rate and with slightly higher pressure, assuming the joint separation is adequate. PA1 (c) When an accessory instrument is used, like a shaver with wall suction, a higher fluid inflow is required to keep up with the increased demand and prevent the joint from collapsing. A higher flow rate but the same set pressure is needed here. Traditionally, the typical solution is to use sterile fluid bags hung above the level of the patient which are connected to the joint by a tube. The bags are raised to obtain more pressure and the flow rate is controlled by using variable clamps on the tubing leading to and away from the patient. The control for the two operations is manual and decided upon by the surgeon. PA1 1. Automatically sequencing and spiking of sterile solution bags as needed to provide an uninterrupted supply of fluid throughout the case. PA1 2. Means for sensing of pressure in the surgical cavity. PA1 3. Means for setting desired cavity pressure manually or automatically in relationship to the patient's blood pressure. PA1 4. Ability to set flow and pressure independently of each other. PA1 5. Controller for maintaining set cavity pressure. PA1 6. Out of Tolerance Flow Controller for adjusting from set flow rate when required to maintain set cavity pressure. PA1 7. A liquid sensor and controller to automatically provide for the flow needs of most any motorized shaver and/or other vacuum related instruments. PA1 8. Auto-sequenced and manual functions displayed on a console including lavage, clear view, prime, drain, burr, pause/run, alarm silence, power on/off, and a surgical diagnostic mode which provides means for setting pressure for distention of surgical cavity with no egress cannula. PA1 9. A help mode (message center) on a console to help users set up or to identify malfunctions.
There are thus two independent factors at work here, the pressure and the flow rate of the irrigation fluid. The function and need for independent control of these two factors can be illustrated by the following situations:
Furthermore, when burring and shaving large amounts of debris forms and can quickly block the exit port leading from the body cavity.
Thus there is a continuing need to improve automated pressure regulating systems and other systems used in arthroscopic or other fluid related procedures in order to provide for automated handling of various aspects of the procedure which the surgeon or supporting staff would otherwise need to handle manually.
There is further a need during arthroscopic surgery--which can last from a few minutes to several hours--to change saline bags. Up to a dozen or more saline bags may be required in an operation, and during a manual spiking of the bag, when infusing saline solution from the bag to the body cavity being operated on, air may be accidentally introduced into the fluid tube leading to the body cavity and may interfere with visualization, and saline solution may be spilled. Saline bags may also run dry unless medical personnel attend to the bags. In addition, often the number of bags needed to complete the operation is not estimated properly. Furthermore, in gravity fed pressurized saline infusions of the type described above, the pressure inside the tube leading to the body cavity can only be varied by raising or lowering the saline bag, which limits the range of pressure achievable and is not accurate.